Rock rains and supersonic winds rage on “lava planets”

Among the most extreme space objects found outside the solar system, lava planets stand out: they are fiery-hot worlds that orbit so close to their star that some of their regions are oceans of molten magma. Scientists have modeled what the weather could be on such an exoplanet and published the study in the Monthly Notices of the Royal Astronomical Society.

Scientists used computer simulations to predict weather conditions on the K2-141b.

By analyzing the exoplanet’s illumination scheme, scientists have found that two-thirds of K2-141b is under constant daylight. This Earth-sized exoplanet belongs to a group of rocky planets orbiting very close to its star. The close distance gravitationally holds it in place – the same side of the planet is always facing the star.

On the “night” side, the temperature drops to -200°C. The “daytime” half of the exoplanet heats up to 3000°C. This high temperature not only melts rocks on the planet’s surface, but also vaporizes them, eventually creating a thin “rock atmosphere”.

It is noteworthy that the atmosphere of stone steam created by the intense heat is subject to precipitation. Similar to the Earth’s water cycle – when it evaporates, rises into the atmosphere, condenses and falls back as rain – so does sodium, silicon monoxide, and silicon dioxide on K2-141b. On Earth, rain falls back into the oceans, where it evaporates again. On K2-141b, the mineral vapor is carried away by supersonic winds to the cold “night” side, where rocks “rain” down into the magma ocean. The streams again end up on the hot side of the exoplanet, where the rocks evaporate again.

“All rocky planets, including Earth, started out as molten worlds, but then quickly cooled and solidified. The lava planets give us a rare glimpse into this stage of planetary evolution, ”emphasizes the importance of the study, Professor Cowen of the Department of Earth and Planetary Sciences at McGill University.

The next step for scientists will be to verify the correctness of these predictions. Researchers now have data from the Spitzer Space Telescope that will give them their first insight into the exoplanet’s actual day and night temperatures. With the launch of the James Webb Space Telescope in 2021, they will also be able to check if the weather on K2-141b matches scientists’ predictions.

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